The Game Boy Cat is one of the many Nyan Cat spoofs found on Nyan.cat.
It has an original white Gameboy as a body that has a green flashing screen. The rest of this Nyan Cat is the same Russian Blue cat.
The cat flies through Space with the default exploding stars, and is trailing a rainbow streak trail that is a gameboy palette rainbow, which is all different shades of green.
The song played is a 8-bit remix of the original song, but the drums in the song are not 8-bit.
The animated gif picture saves as "gb.gif" and the preview icon on the "Pick a Flavor" menu saves as "GB.gif". The title also says "NON-STOP GAMEBOY CAT", but sadly, it is currently stuck as saying it is Nyan Cat.
The detached rainbow glitch is currently present here, but it is not as bad as some other pages.
At one point, Gameboy Cat's page had an Easter Egg; you could find Little Kitty, who is a Russian Blue kitten. Little Kitty is also purposely broken, and will break apart and glitch up like the Glitch Nyan Cat does.
If you clicked on the kitten, it would take you to the Missingnyan Cat 404 page. This would also win you an achievement. The kitten's image saves under the name "missingg.gif"
Sadly, you can't do it anymore unless you use WayBack Machine or use a Nyan.cat 404 link. More information on MissingNyan can be found on the MissingNyan Cat's wiki page,
This Nyan Cat spoof was made by the both the founder of Nyan.cat and the original creator Christ Torries
Little Kitty is what Nyan Cat would look like sat down and without the poptart body.